Band crossings in the positive-parity high-spin states of ${}^{83}\mathrm{Rb}$ and ${}^{85}\mathrm{Y}$

Positive-parity high-spin states in the odd-proton nuclei ${}^{83}\mathrm{Rb}$ and ${}^{85}\mathrm{Y}$ have been populated via the ${}^{68}\mathrm{Zn}{(}^{18}\mathrm{O},p2n)$ reaction at 56 MeV and the ${}^{59}\mathrm{Co}{(}^{28}\mathrm{Si},2p)$ reaction at 99 MeV up to ${(37/2\mathrm{}}^{+})$ and ${(33/2\mathrm{}}^{+}),$ respectively. In both nuclei band crossings have been observed at a spin of $21/2$ and interpreted as resulting from the alignment of a $g_{9/2}$ neutron pair, as in other odd-proton nuclei with 46 neutrons. In the three-quasiparticle high-spin excitations, the observed signature splitting and total Routhian surface calculations indicate that the ${}^{83}\mathrm{Rb}$ nucleus exhibits a well-deformed near-oblate shape. No second alignment has been observed in the yrast sequence of ${}^{83}\mathrm{Rb}$ up to a rotational frequency of 0.95 MeV, indicating that for $Z=37\mathrm{}$ and an oblate shape the breaking of a $g_{9/2}$ proton pair is energetically expensive.